Efficient alternate energy portable fuels are required to end our dependence on fossil fuels. Hydrogen holds the most promise in that reguard. Exploring the paths open for meeting the goal of energy independence is the object of this blog. Hopefully you will find it interesting and informative.

Monday, June 13, 2011

Name That Decay Chain!

There are a lot of studies comparing different energy sources and risk. A lot of the risk is more political than real. Popular opinion means a lot to politicians. Actual risk seems to get lost in the politics.

One comment I saw today was based on a coal versus nuclear study. A large part of the study was a pole of people living near nuclear or coal power plants. That is a big part of the decision of course, what will people vote for, but education of the real risks involve is not as big a deal as I think it should be.

A coal power plant emits a lot of stuff if not scrubbed and filtered. Then if it is scrubbed and filtered, the ash and particulates contain stuff that can be nasty. Heavy metals are a big concern, with radiation a little bit of a concern that looks to be over emphasized.

Coal contains traces of Uranium and Thorium, plus other natural radioactive isotopes. Natural isotopes are generally very long lived, but a there are a few short lived isotopes in the natural decay chains.

For some odd reason, long lived isotopes have a bad reputation. Statistically, it is the short lived ones that are nasty. The short lived are more likely to decay releasing ionizing energy. Uranium-238 has a half life of 4.5 billion years. So a few atoms of Uranium-238 are essentially stable in a biological environment. You would have to ingest a fairly large amount of Uranium-238 to have any radiation harm. It would likely be more harmful as a poisonous heavy metal than a radiation hazard. Think about it. It takes 4.5 billion years for half of the ingested amount to decay. If you ingested 4.5 billion atoms of U-238, 2.25 billion would decay in 4.5 billion years, so only 2.25 would decay per year in your body. Compare 2.25 per year to 4400 per second beta decays normal for a 160 pound (about 75 kilo)person, and that ain't a lot, even if U-238 is 60 times more harmful than K-40. Plutonium-239 is only supposed to be 100 times more harmful than potassium 40, so that makes sense.

I need to build a biological decay table to make it easier for people to compare radiation risk by isotope. Then maybe people can start focusing more on the real risks. A biological decay table would b e the probability of harmful decay energy per microgram of isotope. Then everyone could compare fallout danger to the banana dose or Brazil nut dose.